title: Circulating adropin concentrations in pediatric obstructive sleep apnea: potential relevance to endothelial function.
abstract: OBJECTIVE
  To test the hypothesis that concentrations of adropin, a recently discovered peptide that displays important metabolic and cardiovascular functions, are lower in obstructive sleep apnea (OSA), especially when associated with endothelial dysfunction.
  
  
  METHODS
  Age-, sex-, and ethnicity-matched children (mean age, 7.2 ± 1.4 years) were included into 1 of 3 groups based on the presence of OSA in an overnight sleep study, and on the time to postocclusive maximal reperfusion (Tmax >45 seconds) with a modified hyperemic test. Plasma adropin concentrations were assayed using a commercial enzyme-linked immunosorbent assay kit.
  
  
  RESULTS
  Among controls, the mean morning adropin concentration was 7.4 ng/mL (95% CI, 5.2-16.3 ng/mL). Children with OSA and abnormal endothelial function (EF) (OSA(+)/EF(+) group) had significantly lower adropin concentrations (2.7 ± 1.1 ng/mL; n = 35) compared with matched controls (7.6 ± 1.4 ng/mL; n = 35; P < .001) and children with OSA and normal EF (OSA(+)/EF(-) group; 5.8 ± 1.5 ng/mL; n = 47; P < .001). A plasma adropin concentration <4.2 ng/mL reliably predicted EF status, but individual adropin concentrations were not significantly correlated with age, body mass index z-score, obstructive apnea-hypopnea index, or nadir oxygen saturation. Mean adropin concentration measured after adenotonsillectomy in a subset of children with OSA (n = 22) showed an increase in the OSA(+)/EF(+) group (from 2.5 ± 1.4 to 6.4 ± 1.9 ng/mL; n = 14; P < .01), but essentially no change in the OSA(+)EF(-) group (from 5.7 ± 1.3 to 6.4 ± 1.1 ng/mL; n = 8; P > .05).
  
  
  CONCLUSIONS
  Plasma adropin concentrations are reduced in pediatric OSA when endothelial dysfunction is present, and return to within normal values after adenotonsillectomy. Assessment of circulating adropin concentrations may provide a reliable indicator of vascular injury in the context of OSA in children.
authors.affiliation: Sections of Pediatric Sleep Medicine and Pediatric Pulmonology, Department of Pediatrics, Comer Children's Hospital, Pritzker School of Medicine, University of Chicago, Chicago, IL. Electronic address: dgozal@uchicago.edu.
authors.forename: David
authors.initials: D
authors.lastname: Gozal
authors.forename: Leila
authors.initials: L
authors.lastname: Kheirandish-Gozal
authors.forename: Rakesh
authors.initials: R
authors.lastname: Bhattacharjee
authors.forename: Helena
authors.initials: H
authors.lastname: Molero-Ramirez
authors.forename: Hui-Leng
authors.initials: HL
authors.lastname: Tan
authors.forename: Hari P R
authors.initials: HP
authors.lastname: Bandla
mesh_terms: D001798:Blood Proteins / Q000032:analysis*; D015992:Body Mass Index; D016022:Case-Control Studies; D002648:Child; D004730:Endothelium, Vascular / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000150:complications / Q000175:diagnosis; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010455:Peptides; D017286:Polysomnography; D012372:ROC Curve; D012680:Sensitivity and Specificity; D020181:Sleep Apnea, Obstructive / Q000097:blood*
chemical_list: D001798:Blood Proteins; C568440:Enho protein, human; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010100:Oxygen
keywords: AHI; Apnea-hypopnea index; BMI; Body mass index; EF; Endothelial function; Endothelial nitric oxide synthase; OSA; Obstructive sleep apnea; Oxygen saturation; SpO(2); T(max); TST; Time to postocclusive maximal reperfusion; Total sleep time; eNOS